If today I don't stand out, I will hate myself in future. Even if I get a criminal record it will be a glorious one.

- Edward Yeung, taxi driver

Hong Kong residents had been promised free elections as part of "one country, two systems" principle in which Hong Kong has a different political and government system to that of mainland China.

The current chief executive of Hong Kong, Leung Chun-ying, said before the violence began, that police would treat protestors firmly if they defied the law: "The police are determined to handle the situation appropriately in accordance with the law."

Despite the warning up to 80,000 protestors converged on roads around Admiralty, in Hong Kong's Central district by Sunday evening (local time).

Even if we get beaten up, we cannot fight back. We will win this war with love and peace

- Jimmy Lai

Police in riot gear used pepper spray to try to clear the crowds, but protesters came prepared with goggles and umbrellas in a bid to protect themselves.

Police then baton-charged protesters who responded by shouting abuse and throwing missiles, in violent scenes rarely seen in Hong Kong.

A spokesperson for China's Hong Kong and Macau Affairs Office said China's central government backed the crackdown by police.

In an apparent sign China has been unnerved by the protests, the Chinese social network site Weibo blocked the phrase "Occupy Central", having earlier allowed it.

Publisher Jimmy Lai, one of the main figures behind the pro-democracy movement, said: "The more Hong Kong citizens come, the more unlikely the police can clear up the place. Even if we get beaten up, we cannot fight back. We will win this war with love and peace."